xref: /linux/drivers/clocksource/dw_apb_timer_of.c (revision 03ab8e6297acd1bc0eedaa050e2a1635c576fd11)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (C) 2012 Altera Corporation
4  * Copyright (c) 2011 Picochip Ltd., Jamie Iles
5  *
6  * Modified from mach-picoxcell/time.c
7  */
8 #include <linux/delay.h>
9 #include <linux/dw_apb_timer.h>
10 #include <linux/of.h>
11 #include <linux/of_address.h>
12 #include <linux/of_irq.h>
13 #include <linux/clk.h>
14 #include <linux/reset.h>
15 #include <linux/sched_clock.h>
16 
timer_get_base_and_rate(struct device_node * np,void __iomem ** base,u32 * rate)17 static int __init timer_get_base_and_rate(struct device_node *np,
18 				    void __iomem **base, u32 *rate)
19 {
20 	struct clk *timer_clk;
21 	struct clk *pclk;
22 	struct reset_control *rstc;
23 	int ret;
24 
25 	*base = of_iomap(np, 0);
26 
27 	if (!*base)
28 		panic("Unable to map regs for %pOFn", np);
29 
30 	/*
31 	 * Reset the timer if the reset control is available, wiping
32 	 * out the state the firmware may have left it
33 	 */
34 	rstc = of_reset_control_get(np, NULL);
35 	if (!IS_ERR(rstc)) {
36 		reset_control_assert(rstc);
37 		reset_control_deassert(rstc);
38 	}
39 
40 	/*
41 	 * Not all implementations use a peripheral clock, so don't panic
42 	 * if it's not present
43 	 */
44 	pclk = of_clk_get_by_name(np, "pclk");
45 	if (!IS_ERR(pclk))
46 		if (clk_prepare_enable(pclk))
47 			pr_warn("pclk for %pOFn is present, but could not be activated\n",
48 				np);
49 
50 	if (!of_property_read_u32(np, "clock-freq", rate) ||
51 	    !of_property_read_u32(np, "clock-frequency", rate))
52 		return 0;
53 
54 	timer_clk = of_clk_get_by_name(np, "timer");
55 	if (IS_ERR(timer_clk)) {
56 		ret = PTR_ERR(timer_clk);
57 		goto out_pclk_disable;
58 	}
59 
60 	ret = clk_prepare_enable(timer_clk);
61 	if (ret)
62 		goto out_timer_clk_put;
63 
64 	*rate = clk_get_rate(timer_clk);
65 	if (!(*rate)) {
66 		ret = -EINVAL;
67 		goto out_timer_clk_disable;
68 	}
69 
70 	return 0;
71 
72 out_timer_clk_disable:
73 	clk_disable_unprepare(timer_clk);
74 out_timer_clk_put:
75 	clk_put(timer_clk);
76 out_pclk_disable:
77 	if (!IS_ERR(pclk)) {
78 		clk_disable_unprepare(pclk);
79 		clk_put(pclk);
80 	}
81 	iounmap(*base);
82 	return ret;
83 }
84 
add_clockevent(struct device_node * event_timer)85 static int __init add_clockevent(struct device_node *event_timer)
86 {
87 	void __iomem *iobase;
88 	struct dw_apb_clock_event_device *ced;
89 	u32 irq, rate;
90 	int ret = 0;
91 
92 	irq = irq_of_parse_and_map(event_timer, 0);
93 	if (irq == 0)
94 		panic("No IRQ for clock event timer");
95 
96 	ret = timer_get_base_and_rate(event_timer, &iobase, &rate);
97 	if (ret)
98 		return ret;
99 
100 	ced = dw_apb_clockevent_init(-1, event_timer->name, 300, iobase, irq,
101 				     rate);
102 	if (!ced)
103 		return -EINVAL;
104 
105 	dw_apb_clockevent_register(ced);
106 
107 	return 0;
108 }
109 
110 static void __iomem *sched_io_base;
111 static u32 sched_rate;
112 
add_clocksource(struct device_node * source_timer)113 static int __init add_clocksource(struct device_node *source_timer)
114 {
115 	void __iomem *iobase;
116 	struct dw_apb_clocksource *cs;
117 	u32 rate;
118 	int ret;
119 
120 	ret = timer_get_base_and_rate(source_timer, &iobase, &rate);
121 	if (ret)
122 		return ret;
123 
124 	cs = dw_apb_clocksource_init(300, source_timer->name, iobase, rate);
125 	if (!cs)
126 		return -EINVAL;
127 
128 	dw_apb_clocksource_start(cs);
129 	dw_apb_clocksource_register(cs);
130 
131 	/*
132 	 * Fallback to use the clocksource as sched_clock if no separate
133 	 * timer is found. sched_io_base then points to the current_value
134 	 * register of the clocksource timer.
135 	 */
136 	sched_io_base = iobase + 0x04;
137 	sched_rate = rate;
138 
139 	return 0;
140 }
141 
read_sched_clock(void)142 static u64 notrace read_sched_clock(void)
143 {
144 	return ~readl_relaxed(sched_io_base);
145 }
146 
147 static const struct of_device_id sptimer_ids[] __initconst = {
148 	{ .compatible = "picochip,pc3x2-rtc" },
149 	{ /* Sentinel */ },
150 };
151 
init_sched_clock(void)152 static void __init init_sched_clock(void)
153 {
154 	struct device_node *sched_timer;
155 
156 	sched_timer = of_find_matching_node(NULL, sptimer_ids);
157 	if (sched_timer) {
158 		timer_get_base_and_rate(sched_timer, &sched_io_base,
159 					&sched_rate);
160 		of_node_put(sched_timer);
161 	}
162 
163 	sched_clock_register(read_sched_clock, 32, sched_rate);
164 }
165 
166 #ifdef CONFIG_ARM
dw_apb_delay_timer_read(void)167 static unsigned long dw_apb_delay_timer_read(void)
168 {
169 	return ~readl_relaxed(sched_io_base);
170 }
171 
172 static struct delay_timer dw_apb_delay_timer = {
173 	.read_current_timer	= dw_apb_delay_timer_read,
174 };
175 #endif
176 
177 static int num_called;
dw_apb_timer_init(struct device_node * timer)178 static int __init dw_apb_timer_init(struct device_node *timer)
179 {
180 	int ret = 0;
181 
182 	switch (num_called) {
183 	case 1:
184 		pr_debug("%s: found clocksource timer\n", __func__);
185 		ret = add_clocksource(timer);
186 		if (ret)
187 			return ret;
188 		init_sched_clock();
189 #ifdef CONFIG_ARM
190 		dw_apb_delay_timer.freq = sched_rate;
191 		register_current_timer_delay(&dw_apb_delay_timer);
192 #endif
193 		break;
194 	default:
195 		pr_debug("%s: found clockevent timer\n", __func__);
196 		ret = add_clockevent(timer);
197 		if (ret)
198 			return ret;
199 		break;
200 	}
201 
202 	num_called++;
203 
204 	return 0;
205 }
206 TIMER_OF_DECLARE(pc3x2_timer, "picochip,pc3x2-timer", dw_apb_timer_init);
207 TIMER_OF_DECLARE(apb_timer_osc, "snps,dw-apb-timer-osc", dw_apb_timer_init);
208 TIMER_OF_DECLARE(apb_timer_sp, "snps,dw-apb-timer-sp", dw_apb_timer_init);
209 TIMER_OF_DECLARE(apb_timer, "snps,dw-apb-timer", dw_apb_timer_init);
210